Sources within AEG — the concert promoter behind Jacko’s ill-fated “This Is It” tour and the entity being sued by Jackson’s mother and the three children for wrongful death — say that, despite the singer’s claims, only one of the kids is biologically his.

The company is prepared to uncover that only Blanket, 10, has the King of Pop’s DNA.

His older siblings, Prince, 16, and Paris, 15, had a different sperm donor, the sources say.

“There was a whole lot that Michael Jackson or his family wasn’t and isn’t being forthcoming about,” an AEG source said. “The drug use by Jackson, his use of alcohol, his relationship with his own family, and the identities of the children’s parents.”

Among the evidence AEG could present are sworn affidavits, including one from a mystery woman identified only as “Helena,” who could be Blanket’s mother.

Lawyers for the company also are prepared to present “irrefutable” proof that the Gloved One did not sire Prince and Paris, a source with direct knowledge of the case said. The company is poised to subpoena birth and other records.

Yvette Palazuelos, the presiding judge in the case, earlier this month declined AEG’s request to present evidence about paternity.

However, the company may be allowed to argue paternity issues later in a potential award phase in the case, which began with jury selection April 2 in LA Superior Court.

Legal experts say it doesn’t matter who the biological parents are. They say bringing up paternity is likely meant to embarrass the family.

The Jacksons seek to prove that AEG was complicit in Jacko’s death — hiring his now-convicted personal physician, Dr. Conrad Murray, and pushing the frail singer too hard to perform. Jackson died from acute propofol intoxication in 2009.

Jacko had always claimed to have used his own sperm to father his children. He acknowledged that the mother of Prince and Paris is his former nurse, Debbie Rowe.

The identity of Blanket’s mother, believed to be a Hispanic woman living in the San Diego area, has never been revealed.

But if AEG’s claims are true, the answer to who’s their daddy could come from a long list.

The singer’s former doctor, Arnold Klein, has said he is the biological father of Jacko’s two oldest children. Former bodyguard and karate instructor Matt Fiddes began pressing the family for a DNA test of Paris shortly after the “Thriller” singer’s death. And former child actor Mark Lester claims that he may have fathered Paris.

Jackson family members say they have little doubt who fathered Blanket.

“Blanket looks just like him. There is no doubt that he is Michael’s,” said one relative.

Blanket has even been treated for similar medical problems, including a skin condition, a family source told The Post. Jacko suffered from a disorder called vitiligo.

And Blanket’s love and knowledge of music parallels his dad’s, family members said.